Special Containment Procedures: SCP-1754 is to be contained in an upright position in an airtight acrylic box measuring 40cm X 30cm X 50 cm. Its claws are to be held shut with rubber bands. The floor of the box is to be painted with green pigment. The box is to remain constantly lit. No direct interaction with SCP-1754 is to take place unless properly-sealed biohazard suits are worn.

Vertebrate subjects affected by SCP-1754-1''s smoke are to be contained in standard containment for their species, with appropriate containment modifications to compensate for their physical alterations.

Description: SCP-1754 is an animate, non-sapient assembly composed of smoothed, bleached human bone and other calcified organic materials. The center of SCP-1754 is a human skull, both cranium and mandible, consistent in size and development with that of an adult male between the ages of 35 and 50. Dentition does not match any available records. SCP-1754 is outfitted with two white wheels attached at the temporal styloid processess, the spokes of which are calcified sea stars. SCP-1754 has two thin, wiry appendages which are 15cm long and end in crab claws fashioned from bone. These extend from the mental foramen of the mandible. A white clay smoking pipe, designated SCP-1754-1, is gripped between SCP-1754''s upper and lower teeth. Despite SCP-1754''s calcium-rich composition, its clawed appendages are flexible and its wheels rotate freely.

SCP-1754 is capable of moving on any solid surface at any angle. It uses its claws to roll itself forward on its wheels in the manner of a wheelchair. SCP-1754 stops rolling if its wheels encounter a green1 surface. Aperiodically, it will use its claws either to adjust the position of SCP-1754-1 between its teeth or to pinch nearby personnel. It effectively resists all attempts to remove SCP-1754-1 from its mouth.

Approximately every 1.5 hours, SCP-1754-1 releases a cohesive cloud of opaque white smoke. If SCP-1754 is alone, the smoke rises to the top of the room, where it then dissipates. If SCP-1754 is in the presence of one or more unprotected vertebrate subjects, the smoke moves to surround the closest one (designated an instance of SCP-1754-2). When the instance of SCP-1754-2 has been fully surrounded, the smoke darkens for roughly five seconds before lightening again and dissipating. Following this, SCP-1754-2 has been radically altered to lack a skull. Alternative structures may take the place of the skull, or the organs and tissues of the head may be located elsewhere in the body. Gene sequencing of SCP-1754-2 instances indicates that each instance is no longer a member of its original species, belonging instead to an otherwise-unrecognized group entirely divergent from the vertebrate lineage. The effect is self-consistent, affecting members of the same species in the same manner. For humans, the eyes remain in the same relative position, affixed to independent eye stalks, while the other sensory organs and the brain are located in the neck and chest and are of unfamiliar configurations. Other tested species include chimpanzee, golden lion tamarin, garter snake, trout and ring-necked conure.

Instances of SCP-1754-2 appear healthy and unencumbered by their alterations, to the point where the alterations are normalized from their perspective and unaffected subjects appear similarly alien. Interviews with human instances of SCP-1754-2 suggest that from their perspective, no animal species has ever had a skull, and that they completely lack an understanding of the concept of a skull. Instances of SCP-1754-2 universally express revulsion at the sight of SCP-1754, more so than for non-anomalous skulls. SCP-1754 is not affected by its own smoke.

SCP-1754 is sentient and capable of speech, the sound of which originates from the geometric center of its cranium. The personality expressed through SCP-1754 is an enthusiastic, middle-aged male living at some point in the middle 1960s. SCP-1754 refers to any personnel who interact with it as its "next-door neighbor." Regardless of the nature, quantity, or behavior of listeners, SCP-1754 ceaselessly discusses antiquated topics. These include classic automobiles, female celebrities of the 1960s, and its son''s involvement in the Vietnam War. When it is introduced to an adult male subject who has a wife and children, SCP-1754 may present the subject with an offer to join it and its family for an evening meal "sometime soon." It is unknown how SCP-1754 is able to discern whether a person has a family.

Thus far, SCP-1754 has made no reference to its anomalous appearance or qualities, nor those of SCP-1754-1. SCP-1754 does not seem to remember previously introduced subjects, and has not demonstrated the capacity to learn or connect cause and effect. However, when reintroduced to any instance of SCP-1754-2, it refers to it instead as its "neighbor from down the street" and speaks with a more disappointed tone. SCP-1754 has never referred to itself by any name, and extensive interviews have concluded that it is not possible to conduct meaningful discussion with SCP-1754. In effect, its dialogue is much like that produced by an artificial intelligence.